1. Field of the Invention
This invention is concerned with grout compositions, particularly grout compositions capable of filling either wide or narrow joints between ceramic, cement and other tile.
2. Description of the Prior Art
Tile, such as ceramic or cement tile, is generally employed as a protective and decorative covering for walls and floors in areas which are subject to heavy soiling. It is common, for example, to employ tile in kitchens, bathrooms, family rooms, entry ways, countertops, and the like in the home and in public and commercial buildings. The primary advantage of employing tile in these areas is the relative ease of maintaining and cleaning the tiled surface.
Tile is installed by adhering a plurality of individual tiles to the area to be covered and then filling the spaces between the individual tiles with grout. The conventional grout for ceramic tile is white, premixed grout containing portland cement and additives. Since the ceramic tiles that are employed are usually dense or glazed on their exposed surface, such surface limits penetration. Therefore, these tiles do not readily soil, and, if they become soiled, they are easily cleaned. However, the cement grouts heretofore employed were to some extent porous and readily became soiled. The soiled grouts clearly detracted from the overall appearance of the tiled surfaces.
In addition to having resistance to soiling and ease of cleanability, the grout composition should also be relatively simple to apply. In this regard, it is highly advantageous to have a premixed grout composition which can be applied directly from the container in which it is supplied. It is also quite valuable for any excess grout to be recoverable for use at a later time. The grout composition should also be plastic enough to be readily worked into the spaces between the individual tiles. In addition, the excess grout which is applied should be easily removed from the tile surfaces. The grout should also dry in a relatively short time to a hard finish and with little or no shrinkage or cracking.
U.S. Pat. No. 3,859,233 (hereinafter "the '233 patent") issued to the present inventor, John P. Barker, on Jan. 7, 1975, discloses a grout composition which is resistant to soiling, easily cleaned, workable, fast-drying, easy to clean up during application and which can be provided as a premixed composition. The grout composition there described comprises a thermoplastic film-forming resin latex, preferably an acrylic latex, a white inorganic filler, for example, whiting, and a finely divided clay. The composition could also include thickening agents, silica sand, colorants, agents to control the rate of drying, fungicides, antifoaming agents, and wetting agents. The disclosed grout composition could contain 20-60 parts by weight of white inorganic filler having a particle size passing through 325 mesh (less than 44 microns in diameter), up to about 25 parts of a finely divided 2-20 micron clay, and up to 50 parts by weight of a silica sand having a particle size passing through 70-100 mesh (less than 150 to 210 microns in diameter).
The sand was added to the composition of the '233 patent as an abrasive to assist in the cleaning of excess grout from the surface of the tile during application. The sand content had to be limited to below 50 parts because of dilatancy problems associated with latex compositions containing high loadings of sand.
Dilatancy is the property of a composition whereby it exhibits increased apparent viscosity when subjected to increased shear stresses. The classic example of a dilatant composition is a water and sand mixture, which, when worked by stirring or otherwise, exhibits a vastly increased apparent viscosity. A dilatant grout composition is extremely difficult to mix initially and to work into the joints between the tiles since the shear stresses imposed on the mixture during mixing and application have the effect of increasing the apparent viscosity of the grout composition.
While the grout composition of the '233 patent yields excellent results in narrow tile joints between absorptive tiles (12 to 16% absorption), that is, tile joints having widths in the range of 1/16 to 1/8 of an inch, the grout displays a tendency to crack when used to fill wide joints, that is, joints greater than 1/8 inch in width, i.e., 1/8 to about one inch in width.
It has been suggested by certain manufacturers of prior art grouts, such as the C.E. Kaiser Co. of Houston Texas, manufacturer of K.B. Mastic Grout, that their narrow joint grout compositions can be used to fill wide joints without cracking if a substantial quantity, i.e., at least 25% by weight, of sand extender is added to the commercial grout. However, such efforts to alter narrow joint grout compositions result in undesirably dry and unworkable compositions which are believed to present dilatancy problems similar to those experienced with high sand loadings in the grout of the '233 patent.
Accordingly, it is an object of the present invention to provide a grout composition providing all the advantages of the grout composition of the '233 patent, including resistance to soiling, ease of cleaning, workability, ease of clean-up during application, fast drying and availability in premixed form, while avoiding the cracking and/or dilatancy problems presented by such compositions in wide joints.
Other objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned from the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.